21

5 . 3 H A u P I R I S T E A M S H O v E L

The Haupiri Steam Shovel is a current conservation project

on the West Coast. Since the time of the photograph (Fig. 7),

the surrounding vegetation has been removed and the steam

shovel is now being treated each year with Ensis oil, which

is a short-term preservative. This short-term measure will

continue until funding for a longer term protective treatment

is available.

5 . 4 B I g R I V E R S A w M I l l R O B E y E N g I N E

Even more of a challenge for preservation is the Robey

semi-portable underslung sawmill engine (Fig. 8), which

used to provide power for the Golden Lead Creek Sawmill.

This sawmill produced timber for the nearby coalmines and

the Big River Quartz Mine. The engine’s remote location

(c. 24 km south of Reefton near the end of the Big River Road)

has preserved it from scrap metal merchants and souvenir

hunters.

5 . 5 D E N N I S T O N

The photo shown in Fig. 9 was taken in 2002 near the

top of the Denniston Incline, with the Tasman Sea in the

background. One of the advantages of the West Coast

climate is that items such as the cable wheels on display are

regularly rain–washed. Because they are exposed and have

few crevices and low mass, they also dry out rapidly when

mounted clear of contact with soil or wet vegetation.

The advantages of having open structures that are regularly

washed and do not pond or retain moisture are also

demonstrated by the condition of the tower bases for the

nearby coal bucket cableway system. The original lead-based

alkyd system is still providing adequate protection to the

steel.

Figure 7. The Haupiri steam shovel, West Coast. Photo: Jim Staton, Greymouth Area Office, DOC.

Figure 8. The patent Robey fixed engine.

Figure 9. Cable wheels, located near the top of the Denniston Incline, West Coast.

22

5 . 6 C O A L W A G O N S

Figure 10 shows an example of ‘Q wagons’, which are

now exhibits in a heritage park in Greymouth. They were

lifted off the bogies when they reached the wharf and had

a bottom outlet for emptying into the ship. Some of the

original bituminous coating provides protection in places

but, as can be seen, some of the thinner sheet material has

already corroded away, as a result of contact with wet coal.

5 . 7 R E E F T O N v I S I T O R C E N T R E

As an example of what can be done, Fig. 11 shows a

restored winding engine, which is located in the Reefton

visitor Centre. It is now protected from the damp and salty

West Coast environment (and damage by vandals) by a full

enclosure and a simple protective coating system using alkyd

paint.

5 . 8 u R A P A F E N C E , T A R A N A K I

Figure 12 shows a historic Maori grave site on the Te Rau O Te

Huia Pa Reserve at Onaero, 30 km east of New Plymouth. The

grave fence is said to be an early example of prefabricated

wrought iron dating from the 1860s that may have originated

in Australia. Most of the metalwork is still in reasonable

condition, but there has been severe corrosion and loss of

section at ground level where it is usually damp. It has been

recommended that a concrete plinth be cast around the base

to protect the remaining ironwork.

Figure 10. ‘Q-wagons’, Greymouth.

Figure 11. Restored winding engine, Reefton visitor Centre, West Coast.

Figure 12. urapa fence, Te Rua O Te Huia Pa Reserve, Onaero, Taranaki.

23

5 . 9 M A H I N A P u A C R E E K R A I L W A y B R I D G E

This ‘Howe Truss’ bridge (Fig. 13) is located 5 km south of

Hokitika and just 250 m from the sea. It was built in 1905 with

steel bottom chords and iron truss rods, and was refurbished

by the Department of Conservation (DOC) in April 2000.

The following system was used for restoration: all exposed

metalwork was abrasive blast cleaned to a ‘near-white’ finish

(Sa 2½), primed with 75 μm of an epoxy zinc-rich primer, and

top coated with 200 μm of an epoxy-mastic. The work was

carried out by Gray Bros Engineering of Greymouth under

the supervision of Jim Staton (then at Hokitika Area Office,

DOC), using paint material and inspection services supplied

by International Protective Coatings.

5 . 1 0 D A v I D S O N L O C O M O T I v E

The Davidson Locomotive (Fig. 14)

is thought to be the only surviving

example of a locally built (i.e. at

Hokitika) steam locomotive that

was used on bush railways near

Greymouth. Like the Mahinapua Creek

bridge, this was also refurbished by

Gray Bros Engineering in Greymouth

under Jim Staton’s supervision. After

earlier attempts at painting with epoxy mastic (see Fig. 4), the locomotive

was fully dismantled and new parts were fabricated where required. All of

the metalwork was then abrasive blast cleaned, coated with 80 μm of zinc

metal applied by arc spray, and finished with 120 μm of high-build epoxy

(supplied by Altex Coatings). The end result is shown in Fig. 15.

Figure 14. The Davidson Locomotive before restoration.

Figure 15. The refurbished Davidson Locomotive. Photo: Jim Staton, Greymouth Area Office, DOC.

Figure 13. ‘Howe Truss’ bridge, West Coast.

24

6. Bibliography

6 . 1 R E F E R E N C E S T A N D A R D S

6.1.1 Australian Standards

AS 1627 (series): Metal finishing—preparation and pretreatment of surfaces. Standards Australia,

Sydney.

AS 3894 (series): Site testing of protective coatings. Standards Australia, Sydney.

6.1.2 Australian and New Zealand Standards

AS/NZS 2310 2002: glossary of paint and painting terms. Standards Australia, Sydney, and Standards

New Zealand, wellington. 34 p.

AS/NZS 2312 2002: guide to the protection of structural steel against atmospheric corrosion by

the use of protective coatings. Standards Australia, Sydney, and Standards New Zealand,

wellington. 140 p. plus Amendment 1/2004. 10 p.

AS/NZS 3750 (series): Paints for steel structures. Standards Australia, Sydney, and Standards New

Zealand, wellington.

AS/NZS 4680 2006: Hot-dip galvanized (zinc) coatings on fabricated ferrous articles. Standards

Australia, Sydney, and Standards New Zealand, wellington. 28 p.

6.1.3 International Standards

ISO 2063 2005: Thermal spraying—zinc, aluminium and their alloys. International Organization for

Standardization, geneva. 12 p.

ISO 8501-1 2007: Visual assessment of surface cleanliness. International Organization for

Standardization, göteborg. 74 p.

ISO 9223 1992: Corrosion of metals and alloys—corrosivity of atmospheres—classification.

International Organization for Standardization, genève. 13 p.

6 . 2 R E F E R E N C E T E X T S A N D B A C K G R O u N D R E A D I N G

6.2.1 Corrosion

Boulton, l.H.; wright, g.A. 1983: Fundamentals of metallic corrosion and its prevention. NZ Branch

of the Australasian Corrosion Association, Auckland.

Duncan, J.; Ballance, J. 1988: Marine salts contribution to atmospheric corrosion. Pp. 316–326 in

Dean, S.w. (Ed.): ASTM STP 965 Degradation of metals in the atmosphere. American Society

of Materials and Testing, Philadelphia.

Evans, U.R. 1979: An introduction to metallic corrosion. 3rd edition. Arnold, london.

Fontana, M.B.; greene, N.P. 1978: Corrosion engineering. Mcgraw-Hill, New york.

King, g.A.; O’Brien, D.J. 1995: The influence of marine environments on metals and fabricated coated metal

products, freely exposed and partially sheltered. Pp. 167–192 in Kirk, w.w.; lawson, H. (Eds):

ASTM STP 1239 Atmospheric corrosion. American Society of Materials and Testing, Philadelphia.

Spence, J.w.; Haynie, F.H.; lipfert, F.w.; Cramer, S.D.; McDonald, l.g. 1992: Atmospheric corrosion model

for galvanized steel structures. Corrosion 48(12): 1009–1019. National Association of Corrosion

Engineers, Philadelphia.

Uhlig, H.H.; Revie, R.w. 1985: Corrosion and corrosion control. wiley, New york.

25

6.2.2 Protective coatings

Clifton, C. (Ed.) 2005: New Zealand Steelwork Corrosion Coatings guide. HERA Report R4-133, NZ

Heavy Research Association, Manukau City.

Eade, J. (Ed.) 1999: After-fabrication hot dip galvanizing. 15th edition. galvanizers Association of

Australia, Melbourne.

Hare, C.H. 1994: Protective coatings: fundamentals of chemistry and composition. SSPC (The Society

for Protective Coatings), Pittsburgh.

Munger, C.g.; Vincent, l.D. 1999: Corrosion prevention by protective coatings. 2nd edition. NACE,

Houston.

SSPC 2000: Painting manual, Vol. 2. Systems and specifications. 8th edition. SSPC (The Society for

Protective Coatings), Pittsburgh.

SSPC 2002: Painting manual, Vol.1. good painting practice. 4th edition. SSPC (The Society for

Protective Coatings), Pittsburgh.

6.2.3 Miscellaneous

DOC (Department of Conservation) 2001: Historic heritage workshop proceedings (unpublished).

Department of Conservation, wellington.

Kemp, E.l.; Sande, T.A. (Eds) 1978: Historic preservation of engineering works. Proceedings of an

ASCE Conference, New Hampshire.

Mandeno, w.l. 1991: Painting State Highway Bridges—past, present & future. Journal of Protective

Coatings & Linings 8(1): 44–51.

Mandeno, w.l. 2003: Steel surface preparation standards. Corrosion & Materials 28(2): S5–S8.

Mandeno, w.l. 2006: Performance specified maintenance contract on the Auckland Harbour

bridge—a review. Proceedings of Austroads 6th bridge conference, Perth.

wright, l. 1993: Big River Quartz Mine. Friends of waiuta Inc., Invercargill.

26

Appendix 1

P R O D u C T S A N D S E R v I C E P R O v I D E R S

The following is a list of coating manufacturers and distributors in

New Zealand. It should be noted that this list is not exhaustive, but rather

is intended as a good starting point for anyone wishing to restore or protect

iron or steelwork. New Zealand manufacturers who are ‘Recognised’ by the

Australian Paint Approvals Scheme (APAS) are denoted by an asterisk (*).

Contact information is correct as at September 2007.

Akzo Nobel Coatings Ltd

Tel (09) 828 3009

Fax (09) 828 1129

Private Bag 19-995

Avondale, AuCKLAND

(Mfr. of ‘International’ coatings)

Altex Coatings Ltd*

Tel (07) 541 1221

Fax (07) 541 1310

PO Box 142, TAuRANGA

(Mfr. of ‘Devoe’ coatings)

Ameron NZ Ltd

Tel (09) 573 2100

Fax (09) 573 0634

PO Box 22-122

Otahuhu, AuCKLAND

Fortec Paints Ltd

Tel (09) 444 7244

Fax (09) 444 3545

PO Box 100-208

NSMC, AuCKLAND

(Agents for ‘Wasser’ & ‘Xymax’ )

Orica NZ Ltd*

Tel (04) 576 6400

Fax (04) 576 6425

PO Box 30-749, LOWER HuTT

(Mfr. of ‘Dulux’ & ‘ICI’ coatings)

Polymer Developments Group Ltd

Tel 0800 999 001

Fax (09) 274 1405

PO Box 58-256

Greenmount, AuCKLAND

(Mfr. of ‘Carboline’ coatings)

Resene Paints Ltd*

Tel (04) 577 0500

Fax (04) 577 0603

PO Box 38-242, WELLINGTON

Wattyl (NZ) Ltd

Tel (09) 828 4009

Fax (09) 820 3271

PO Box 1545, AuCKLAND

(Agent for ‘Sigma’ coatings)

27

Appendix 2

P R O T E C T I v E C O A T I N G S P E C I F I C A T I O N S

1. Clear coating system

2. Aluminium epoxy coating system

3. Moisture cure urethane system

4. Alkyd coating system

5. High performance coating system

28

S y S T E M 1 ( C l E A R C O A T I N g )

1. Scope

This specifies a protective coating system to be used to preserve unpainted wrought iron or

steel work outdoors that is exposed to contact by the public and/or animals, where a durable

finish coat is required that does not significantly change the original rusted appearance of

the item.

2. Materials

2.1 Sealer/primer

The primer shall be an approved low viscosity 100% volume solids epoxy in a clear colour.

Examples of this material are Altex ‘Altra~lock 577’ and their low temperature/rapid cure

version ‘Altra~lock 576’, Ameron’s ‘Amerlock Sealer’, Carboline’s ‘Rustbond Penetrating

Sealer’, and Resene’s ‘ArmourBond’.

2.2 Finish coat

The finish coat shall be an approved acrylic modified polyurethane or polysiloxane in a clear

colour with a flat or low-gloss finish.

Examples of this material are Altex ‘Devthane 379’ + ‘Flattening Agent’, Ameron’s ‘PSX 700’,

Carboline’s ‘Carboline 133 HB’, and Resene’s ‘Uracryl 404’.

3. Preparation

where surfaces are covered with biogenic surface contamination such as algae, moss and

lichens, pretreat with a 1.5% solution of benzylalkonium chloride biocide (e.g. ‘wet’n Forget’,

‘Clene Up’, ‘Ultramate’, or ‘Synthecol Quad lF’) in water applied by brush or low-pressure

garden spray and leave for at least 24 hours. Biocide to be applied when no rain is forecast

for at least 24 hours. Note that this material is non-bleaching and biodegrades at below

20 ppm.

Carefully remove loosely adherent rust scale, flaking paint (if present), dirt and other surface

deposits by hand tools such as chipping hammer, scrapers and wire brush. Following this,

thoroughly scrub all surfaces with a nylon brush using water and a non-ionic detergent

(Castrol ‘Flexiclean’ or equivalent), followed by a low-pressure fresh water rinse to remove

any soluble non-visible contaminants from pits and crevices.

4. Application

Apply a single coat of the sealer/primer followed by two coats of the finish coat material

(all from the same manufacturer wherever possible), allowing the recommended cure time

between coats. Apply all coatings by brush to dry surfaces at above 10°C, working material

into all crevices and any residual rust. Do not overbuild the primer and remove excess material,

e.g. from ponding in pits.

Coatings are to be mixed and applied in accordance with the manufacturer’s instructions.

A copy of the product data sheet and material safety data sheet (MSDS) shall be available on

site for all materials used including thinners. Follow the manufacturer’s health and safety

recommendations.

29

S y S T E M 2 ( A l U M I N I U M E P O X y C O A T I N g )

1. Scope

This specifies a protective coating system to be used to preserve wrought iron or steel work

outdoors that is exposed to contact by the public and/or animals, where a metallic aluminium

finish coat is required and preparation by abrasive blasting is not permitted or possible.

2. Materials

2.1 Epoxy mastic

The coating shall be an approved high-build, aluminium pigmented, surface-tolerant epoxy

mastic that conforms to AS 3750.1. Examples of this material are Altex ‘Bar Rust 236’, Ameron’s

‘Amerlock 2, Carboline’s ‘Carbomastic 15’ and Resene’s ‘Alumastic’.

3. Preparation

where surfaces are covered with biogenic surface contamination such as algae, moss and

lichens, pretreat with a 1.5% solution of benzylalkonium chloride biocide (e.g. ‘wet’n Forget’,

‘Clene Up’, ‘Ultramate’, or ‘Synthecol Quad lF’) in water applied by brush or low-pressure

garden spray and leave for at least 24 hours. Biocide to be applied when no rain is forecast

for at least 24 hours. Note that this material is non-bleaching and biodegrades at below

20 ppm.

Remove loosely adherent rust scale, flaking paint (if present), dirt and other surface deposits

by hand tools such as chipping hammer, scrapers and wire brush. Following this, thoroughly

scrub all surfaces with a nylon brush using water and a non-ionic detergent (Castrol ‘Flexiclean’

or equivalent), followed by a low-pressure fresh water rinse to remove any soluble non-visible

contaminants from pits and crevices.

4. Application

Apply at least two spray coats or three heavy brush coats of epoxy mastic, allowing the

recommended cure time between coats. Apply all coatings to dry surfaces at above 10°C,

working material into all crevices and any residual rust, and ensuring a good build is achieved

on all edges.

Coatings are to be mixed and applied in accordance with the manufacturer’s instructions.

A copy of the product data sheet and material safety data sheet (MSDS) shall be available on

site for all materials used including thinners. Follow the manufacturer’s health and safety

recommendations.

30

S y S T E M 3 ( M C U C O A T I N g )

1. Scope

This specifies a protective coating system to be used to preserve wrought iron or steel work

outdoors that is exposed to contact by the public and/or animals, where a durable finish coat

is required that can be applied under cold and/or damp conditions. This system shall also be

used to overcoat/encapsulate old systems where lead-based primers have been used.

2. Materials

2.1 Sealer/primer

The primer shall be an approved aromatic moisture cure urethane (MCU) sealer/primer

complying with AS/NZS 3750.18.

Examples of this material are Carboline’s ‘E21 Primer’, and Fortec’s ‘wasser MC-Prepbond’,

and ‘Xymax Monolock’.

2.2 Intermediate/tie coat

This shall be an approved aromatic MCU tiecoat that is pigmented with micaceous iron oxide

(MIO) suitable for overcoating aged alkyds.

Examples of this material are Fortec’s ‘wasser MC-Miomastic’ and ‘Xymax Xyguard’.

2.3 Finish coat

This shall be an approved aliphatic MCU pigmented with MIO coloured light grey in a low

gloss finish or, where a coloured finish is required, an approved acrylic-modified two-pack

polyurethane (2PU).

Examples of the MCU material are Fortec’s ‘wasser MC-Ferrox B’ and Xymax ‘Bridge Finish’.

For examples of 2PU, refer to System1 (e.g. Resene’s ‘Uracryl’ range).

2.4 Tar-based finish coat

where a tar-based coating is required for steel work in contact with soil or water, or when

previously coated with coal tar epoxy or a bituminous material (e.g. coal wagons), use a high-

build MCU, preferably manufactured with a synthetic tar.

An examples of this material is Fortec’s ‘wasser MC-Tar’. An alternative is Carboline’s

‘Polyline 1300’ (note a 2 pack material which contains coal-tar also requires additional safety

precautions during application).

Continued on next page

31

3. Preparation

where surfaces are covered with biogenic surface contamination such as algae, moss and

lichens, pretreat with a 1.5% solution of benzylalkonium chloride biocide (e.g. ‘wet’n

Forget’, ‘Clene Up’, ‘Ultramate’, or ‘Synthecol Quad lF’) in water applied by brush or low-

pressure garden spray and leave for at least 24 hours. Biocide to be applied when no rain

is forecast for at least 24 hours. Note that this material is non-bleaching and biodegrades at

below 20 ppm.

Remove loosely adherent rust scale, flaking paint (if present), dirt and other surface

deposits by hand tools such as chipping hammer, scrapers and wire brush. Following this,

thoroughly scrub all surfaces with a nylon brush using water and a non-ionic detergent

(Castrol ‘Flexiclean’ or equivalent), followed by a low-pressure fresh water rinse to remove

any soluble non-visible contaminants from pits and crevices.

4. Application

Apply a single coat of the sealer/primer to areas of bare steel followed by a full coat of

the intermediate/tiecoat, then apply a single finish coat in the required gloss level and

colour allowing the recommended cure time between coats. when using the tar-based finish

coat, apply two heavy coats directly over primed surfaces. Apply all coatings by brush

and/or roller, working material into all crevices and any residual rust. where a rapid cure

is required, the primer and intermediate coat may have their cure accelerated, but this

isocyanate-modified material shall not be applied to damp surfaces.

Coatings are to be mixed and applied in accordance with the manufacturer’s instructions.

A copy of the product data sheet and material safety data sheet (MSDS) shall be available on

site for all materials used including thinners. Follow the manufacturer’s health and safety

recommendations.

System 3—continued

32

S y S T E M 4 ( A l K y D C O A T I N g )

1. Scope

This specifies a protective coating system to be used to preserve previously painted

wrought iron or steel work outdoors, where a traditional finish coat is required using alkyd

(i.e. thinned with turpentine) paint to preserve the original appearance of the item.

2. Materials

2.1 Penetrating liquid

The penetrating liquid shall be an approved low viscosity oil-based material with corrosion

inhibiting pigmentation.

Examples of this material are Altex ‘RIPO’ and wattyls ‘Killrust Fishoilene’.

2.2 Metal primer

The primer shall be an approved zinc phosphate pigmented, high-build alkyd primer complying

with AS 4089, Type 2.

Examples of this material are Altex ‘High Build Rust Barrier’, wattyl’s ‘Killrust Metal Primer’

and Resene’s ‘Rust-Arrest’.

2.3 Finish coat

The finish coat shall be an approved alkyd enamel in grey MIOX, red-oxide, or black colour.

Examples of this material are Altex ‘Isotal Ferrox’, wattyl’s ‘Killrust Roof Paint’ and Resene’s

‘Micabond’ or ‘Supergloss Enamel’.

3. Preparation

where surfaces are covered with biogenic surface contamination such as algae, moss and

lichens, pretreat with a 1.5% solution of benzylalkonium chloride biocide (e.g. ‘wet’n Forget’,

‘Clene Up’, ‘Ultramate’, or ‘Synthecol Quad lF’) in water applied by brush or low-pressure

garden spray and leave for at least 24 hours. Biocide to be applied when no rain is forecast for

at least 24 hours. Note that this material is non-bleaching and biodegrades at below 20 ppm.

Carefully remove loosely adherent rust scale, flaking paint (if present), dirt and other surface

deposits by hand tools such as chipping hammer, scrapers and wire brush. Collect any flakes

of lead paint and remove from site for safe disposal, then thoroughly scrub all surfaces with

a nylon brush using water and a non-ionic detergent (Castrol ‘Flexiclean’ or equivalent),

followed by a low-pressure fresh water rinse to remove any soluble non-visible contaminants

from pits and crevices.

4. Application

Apply a coat of penetrating liquid to all crevices, then two coats of the metal primer to all bare

surfaces, followed by two full coats of the finish coat material, allowing the recommended

dry time between coats. Apply all coatings by brush to dry surfaces at above 10°C, working

material into all crevices and any residual rust. Remove excess penetrating material, e.g. from

ponding in pits, by wiping with a clean rag before priming.

Coatings are to be mixed and applied in accordance with the manufacturer’s instructions.

A copy of the product data sheet and material safety data sheet (MSDS) shall be available on

site for all materials used including thinners. Follow the manufacturer’s health and safety

recommendations.

33

S y S T E M 5 ( H I g H P E R F O R M A N C E C O A T I N g )

1. Scope

This specifies a protective coating system to be used to preserve wrought iron or steel work

outdoors that is exposed to contact by the public and/or animals, where a very durable

system and high gloss chemical-resistant finish coat is required. This system should only be

used where abrasive blasting is possible.

2. Materials

2.1 Primer

The primer shall be an approved inorganic zinc silicate primer complying with AS/NZS

3750.15.

Examples of this material are Altex’s ‘Zinc Silicate 8641’, Carboline’s ‘Carbozinc 11’, and

Resene’s ‘Zincilate 11’.

Alternatively, the steel surface may be primed with thermally applied zinc metal (99.9%

purity).

2.2 Intermediate coat

This shall be an approved high-build epoxy coating complying with AS/NZS 3750.14.

Examples of this material are Altex’s ‘Bar-Rust 236, Carboline’s ‘893 FD’, and Resene’s

‘Armourcote 515’.

2.3 Finish coat

This shall be an approved high gloss aliphatic polyurethane complying with AS/NZS 3750.6.

Examples of this material are Altex’s ‘Devthane 379’, Carboline’s ‘134’, and Resene’s ‘Imperite

413’.

3. Preparation

Remove any grease or oil by solvent cleaning or detergent washing, then remove rust and scale

by abrasive blasting to AS 1627.4 to achieve a ‘Commercial’ or ‘Sa 2’ standard of cleanliness

in accordance with ISO 8501-1. If dry blasting, follow with a low-pressure fresh water rinse

to remove any soluble non-visible contaminants from pits and crevices, then re-abrasive blast

to achieve a ‘Near-white’ or ‘Sa 2½’ standard of cleanliness in accordance with ISO 8501-1,

and with a surface profile of between 50 and 75 µm. In coastal locations (to aid in removal of

marine salts), leave overnight before reblasting.

4. Application

Apply a single coat of the zinc silicate primer to the prepared steel to achieve a minimum

average dry film thickness (DFT) of 75 µm, followed by the high-build epoxy in one or more

coats to give a total minimum DFT of 275 µm. (Alternatively, this can be achieved by arc

spraying 200 µm of zinc metal and applying by spray a 75 µm seal coat of epoxy.) Apply a

single finish coat in the required gloss level and colour of the polyurethane with a DFT of

75 µm, allowing the recommended cure time between coats.

Coatings are to be mixed and applied in accordance with the manufacturer’s instructions.

A copy of the product data sheet and material safety data sheet (MSDS) shall be available on

site for all materials used including thinners. Follow the manufacturer’s health and safety

recommendations.